1. Field of the Invention
The present invention relates to an analyzer device for a VOR navigational receiver which utilizes a first receiver section in which the reference phase, transmitted in the form of a frequency modulation, is available in demodulated form as reference signal, and a second receiver section in which the rotational phase, depending upon the particular direction of the antenna pattern, occurs in the form of an amplitude modulated rotating signal, and in which angular information in the azimuthal plane is obtained from a comparison of the reference phase with the rotational phase.
2. Description of the Prior Art
From German Pat. No. 1,591,904 as well as from French Pat. No. 1,435,126, phase-measuring devices are known in which an oscillator provides output pulses which are applied to a counter as counting pulses. The frequency of this oscillator is a whole number multiple of 360 and the counting operation itself is started when the phase reference signal has a zero transit. The next zero transit of the oscillation whose phase is to be measured, ends the counting operation. The count thus reached is therefore proportional to the phase angle between the two oscillations. Because the known devices use a built-in oscillator which furnishes the counting pulses, frequency deviations in this oscillator are directly incorporated into the measurement and affect its accuracy.
From the magazine "Aerokurier" (Aerocourier) 3/1974 pages 148 to 149, a VOR receiver is known in which an angle is displayed together with further information in the form of a TO or FROM indication. A pilot thus, in relation to a specific ground station, not only has a piece of absolute angular information in the azimuthal plane (derived from a specific reference direction), but also has two pieces of information which must be correspondingly combined. This makes appreciation of the instrument reading complex and there is the risk that if the wrong combination is chosen then the wrong course will be flown.